1. Field of the Invention
The present invention relates to glass packaging (jar, wide-mouth flask, bottle, decanter, etc.) having a rim which constitutes a surface of any desired geometry (annular, oval, substantially rectangular or other) and on which a metal seal is heat-sealed, providing a hermetic closure.
The rim is initially coated with a layer of heat-sealing primer, while the seal comprises a layer of thermoplastic resin which allows heat-sealing to take place by the application of an adequate temperature and of pressure.
2. Description of the Related Art Including Information Disclosed Under 37 CFR 1.97 and 1.98
The problems confronting a user of this technique are of a number of orders.
It is, of course, of prime importance to ensure durable hermetic closure under the conditions in which the packaged product is used, which may include changes in temperature and even biological transformations such as fermentation. The preservation of the product while respecting the conditions laid down for that purpose must also be ensured.
The major problem posed by this technique lies in the often excessive force to be expended in order to open the packaging by peeling of the seal. This excessive force may make the operation difficult for a young child or a relatively weak person. Moreover, this difficulty in opening is often accompanied by the tearing of the seal into a number of pieces, accompanied by residues of thermoplastic resin from the seal which are left adhering to the heat-sealing surface.
Consideration might be given to employing complex, multilayer polymeric seals incorporating a cohesive fracture layer, but the heat-sealing surface of the opened packaging likewise has sticky residues of thermoplastic resin originating from the seal.
The objective of the inventors was therefore to solve these problems.